US6174302B1 - Disposable diaper - Google Patents

Abstract

A disposable diaper includes a liquid-permeable topsheet, a liquid-impermeable backsheet and an absorbent core disposed therebetween. The core has its transversely opposite side edges curved inwardly of the core. Portions of the topsheet and the backsheet extending outward beyond the side edges of the core are put flat and bonded together. Such extensions are folded inwardly of the diaper along straight folding lines extending longitudinally outside the respective curved side edges of the core so as to form a pair of leak-proofing cuffs. First and second elastically stretchable/contractile members are bonded under appropriate tension to the respective leak-proofing cuffs along its inner side edges and the straight folding lines.

Description

BACKGROUND OF THE INVENTION

This invention relates to disposable diapers for absorption and containment of urine and other body exudates.

Japanese Patent Application Disclosure (Kokai) No. Hei7-289584 discloses a disposable diaper including leak preventing cuffs normally biased to rise up on an inner surface of the diaper. These cuffs are composed of substantially crescent-shaped elastic sheets which extend longitudinally of the diaper and are bonded under tension along their arc-shaped edges to the inner surface of the diaper. Such an arrangement makes it possible to form the cuffs having their heights gradually decreasing from the maximal dimension in the crotch region to the minimal dimension in the proximity of the waist-opening. The diaper provided with such cuffs is not bulky in the proximity of the waist-opening and therefore convenient for wearing it.

With this known diaper, a main body of the diaper must be previously curved in order to bond the crescent-shaped cuffs to the main body. A step of bonding the cuffs to the main body previously curved in the corresponding shape inevitably obstructs a desired speed-up of production. In addition, use of an elastic sheet as material for these cuffs necessarily increases the material cost.

SUMMARY OF THE INVENTION

An object of the invention is to solve the problems encountered by the conventional diaper provided with the foregoing leakage proofing cuffs.

According to the invention, there is provided a disposable diaper comprising a main body serving for absorption of body fluids, the main body comprising, in turn, a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween, and a pair of elastically stretchable/contractile leakage proofing cuffs formed along transversely opposite side edges of the main body, the leak preventing cuffs extending longitudinally of the diaper and being collapsed inwardly of the main body onto an inner surface thereof under an elastic bias to rise up the leakage proofing cuffs on the inner surface, wherein the core is defined by front and rear ends and opposite side edges, the side edges being curved inwardly of the core at least along longitudinally middle parts of the side edges, and each of the leakage proofing cuffs at least partially is formed by portions of the topsheet and the backsheet extending outward beyond transversely opposite side edges of the core and includes a lower portion extending in a region defined between the curved side edge of the core and a straight folding line extending longitudinally outside the curved side edge and an upper portion formed by folding an extension of the lower directed transversely of the main body along the straight folding line onto the inner surface of the main body, wherein elastically stretchable/contractile members are secured under appropriate tension to the leak preventing cuffs at least in the proximity of the folding line and in the proximity of an inner side edge of the upper portion extending in parallel to the folding line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view depicting a part cutaway diaper according to the invention;

FIG. 2 is a sectional view taken along a line II—II in FIG. 1;

FIG. 3 is a sectional view taken along a line III—III in FIG. 1; and

FIG. 4 is a perspective view depicting the diaper as being curved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Details of a disposable diaper according to the invention will be more fully understood from the description given hereunder with reference to the accompanying drawings.

Referring to FIGS. 1,2 and3, adiaper1 includes amain body2 lying in the middle transversely thereof and a pair ofside flaps3 extending outward from transversely opposite side edges of themain body2.

Themain body2 is composed of a liquid-permeable topsheet6, a liquid-impermeable backsheet7 and a liquid-absorbent core8 disposed between these twosheets6,7. In FIG. 1, most of thecore8 is depicted with its outline by a broken line. As will be apparent from FIG. 1, thecore8 is defined by longitudinallyopposite ends11,12 and transverselyopposite side edges13,13 which are curved inwardly of thecore8. A distance between an imaginary straight line connecting longitudinally oppositeends16,17 of eachside edge13 and thisside edge13 is preferably dimensioned to be 5˜40 mm at the middle of thisside edge13.

Thetopsheet6 and thebacksheet7 extend outward beyond theends11,12 and theside edges13 of thecore8 and are put flat and bonded together by means of hot melt adhesive (not shown) along their extensions. The extensions of thetopsheet6 and thebacksheet7 bonded together in this manner are folded back alongrespective folding lines18 defined by the foresaid imaginary lines connecting the longitudinallyopposite ends16,17 of therespective side edges13,13 so that these extensions are collapsed toward an inner side of themain body2 with thetopsheet6 lying inside. Thus a pair ofleak preventing cuffs25 are formed at transversely opposite side edges of themain body2. Specifically, portions of thesetopsheet6 and thebacksheet7 extending between therespective side edges13 and the associatedfolding lines18 define a pair oflower portions21 of theleak preventing cuffs25. Portions of thetopsheet6 and thebacksheet7 collapsed toward themain body2 defineupper portions22 of theleak preventing cuffs25. These lower andupper portions21,22 of theleak preventing cuffs25 form together the pair ofleak preventing cuffs25 extending along longitudinally opposite side edges of themain body2, respectively. Each of theupper portions22 has its front andrear ends23,24 extending outward beyond the longitudinallyopposite ends11,12 of thecore8 and bonded to the inner side of themain body2 by means of suitable adhesive (not shown). Theupper portions22 have theirinner side edges26,26 longitudinally extending in parallel to therespective folding lines18.

Each of theleak preventing cuffs25 including the lower andupper portions21,22 is provided with first and second elastically stretchable/contractile members27,28. The first elastically stretchable/contractile member27 extends along theinner side edge26 between the front andrear ends23,24. The second elastically stretchable/contractile member28 extends along an intermediate part of thefolding line18 between the front andrear ends23,24 and is shorter than the first elastically stretchable/contractile member27. These first and second elastically stretchable/contractile members27,28 are secured under appropriate tension to the inner surface(s) of thetopsheet6 or/and thebacksheet7. The first elastically stretchable/contractile members27,27 preferably extend in parallel to the respectiveinner side edges26,26. On the other hand, it is not essential for the second elastically stretchable/contractile members28 to extend in parallel to therespective folding lines18. Specifically, the second elastically stretchable/contractile members28 may be more or less curved or bent so long as they extend substantially along therespective folding lines18 longitudinally of theleak preventing cuffs25. It is also possible to form these second elastically stretchable/contractile members28 by a plurality of elastically stretchable/contractile elements extending in parallel one to another, respectively.

The pair ofside flaps3 have theirinner side edges31,31 bonded on their inner surfaces by means of hot melt adhesive32 to an outer surface of themain body2 in a region of therespective side flaps3 defined between therespective side edges13,13 of thecore8, so that bonding of theseflaps3 may not restrict movement of thelower portion21 of theleak preventing cuffs25, in other words, since each of thelower portions21 is not bonded to a region of theflaps3 extending outward of theside edge13, thelower portions21 can move with respect to theflaps3. Each of theflaps3 are composed, in itsremainder portion33, of front andrear wings34,36 adapted to cover the wearer's waist regions and anotch37 extending between thewings34,36 so as to surround the wearer's leg. Each of therear wings36 is provided with an elastically stretchable/contractile member41 extending circumferentially of the wearer's waist regions and each of thenotches37 is provided with an elastically stretchable/contractile member42 extending circumferentially of the wearer's leg. These elastically stretchable/contractile members41,42 are secured to therear wings36 and thenotches37, respectively, under appropriate tensions. These elastically stretchable/contractile members41,42 are depicted as they are exposed on an inner surface of theflap3 and intended to come in contact with the wearer's skin. It should be understood, however, that the wearer's skin may be protected from direct contact with these elastically stretchable/contractile members41,42 by laminating two sheets to form theflap3 and securing themembers41,42 to an inner surface at least one of these two sheets. Therear wings36 are provided in the proximity of their outer side edges withtape fasteners38 adapted to be releasably anchored to outer surfaces of the respectivefront wings34.

FIG. 4 is a perspective view depicting the posture the diaper of FIG. 1 takes when it is put on the wearer's body. As depicted, the diaper is curved longitudinally with thetopsheet6 lying inside. As the diaper is curved in this manner, the first and second elastically stretchable/contractile members27,28 contract, respectively. Consequently, the lower andupper portions21,22 of theleak preventing cuffs25 rise up on theside edges13 of thecore8 so as to be spaced from inner surfaces of therespective flaps3 and theupper portions22 rise up on the inner surface of themain body2. In this way, theleak preventing cuffs25 form relatively large leakage preventing walls each presenting a substantially crescent shape. In this posture, each of theleak preventing cuffs25 has a height corresponding to a dimension from the associatedside edge13 of thecore8 to theinner side edge26 of the associatedupper portion22. This dimension is maximum in the longitudinally middle region (crotch region) of the main body and gradually decreases toward the front and rear ends of thecore8. Theleak preventing cuffs25 of such an arrangement can effectively prevent a quantity of body fluids discharged on the diaper from leaking through a gap possibly formed between the wearer's body and the diaper when the diaper slips down along the wearer's body.

To implement the invention, a nonwoven fabric or a porous plastic sheet may be used to form thetopsheet6 and a plastic sheet may be used to form thebacksheet7. Thecore8 may be formed by fluff pulp or a mixture of fluff pulp and polymer powder of high absorptivity. A nonwoven fabric, a plastic sheet or a laminate of them may be used to form theflaps3. It is not important whether these materials for theflaps3 is hydrophobic or hydrophilic so far as they are breathable and liquid-permeable. Bonding of the respective members may be achieved not only by using suitable adhesive such as hot melt adhesive but also by using a heat-sealing technique so long as the members to be bonded are of heat-sealable nature.

Theleak preventing cuffs25 depicted as the laminate of thetopsheet6 and thebacksheet7 may be implemented in the other various manners without departing from the scope of the invention. For example, regions of the respectiveleak preventing cuffs25 extending in the proximity of therespective side edges13,13 of thecore8 may be formed by thetopsheet6 and thebacksheet7 laminated one upon another and the remainder regions may be formed by thebacksheet7 alone or replaced by waterproof sheets prepared separately of thetopsheet6 and thebacksheet7. Instead of separately preparing the pair offlaps3 to be bonded to themain body2 along its transversely opposite side edges, respectively, it is also possible to bond themain body2 to an inner surface of a single hourglass-shaped sheet in its middle region and thereby to form the pair offlaps3.

The disposable diaper includes a pair of leak preventing cuffs adapted to rise up on the inner surface of the diaper along the transversely opposite and inwardly curved side edges of the core. These leak preventing cuffs have their heights which are maximal in the crotch region and gradually decrease in the waist regions. The invention makes it unnecessary to prepare the leak preventing cuffs of such configuration separately of the main body as it has conventionally been the case and, in consequence, a corresponding increase in manufacturing cost due to such separately prepared members can be avoided.

Claims (13)

What is claimed is:

1. A disposable diaper comprising:

a main body for absorbing and containing body exudates, said main body including a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween, said liquid-absorbent core having front and rear ends, a pair of opposite side edges that are curved inwardly at least along a longitudinal middle portion thereof;

a pair of elastically stretchable/contractile leak preventing cuffs formed along transversely opposite side edges of said main body, said leak preventing cuffs extending longitudinally of said diaper and being collapsible inwardly of said main body onto an inner surface of said main body under an elastic bias which causes said leak preventing cuffs to rise up on the inner surface; and

a pair of side flaps extending outward from transversely opposite side edges of said main body, each of said side flaps being provided with an elastically stretchable/contractile member extending longitudinally of said side flap,

said liquid-absorbent core being defined by front and rear ends and a pair of opposite side edges, said side edges being curved inwardly at least along longitudinally middle portions thereof

each of said leak preventing cuffs is at least partially formed by portions of at least one of said topsheet and said backsheet which extend outward beyond transversely opposite side edges of said core and includes a lower portion extending in a region defined between said side edge of said core and an outer fold line extending longitudinally outside said curved side edge of said core, each of said leak preventing cuffs further includes an upper portion formed by folding an extension of said lower portion directed transversely of said main body along said outer fold line onto said inner surface of said main body, wherein elastically stretchable/contractile members extending longitudinally of said main body are secured under tension to said leak preventing cuffs at least in the proximity of said outer fold line and in the proximity of an inner side edge of said upper portion extending in parallel to said outer fold line.

2. A disposable diaper according to claim1, wherein each of said leak preventing cuffs is bonded at longitudinally opposite ends to said main body.

3. A disposable diaper according to claim2, wherein said longitudinally opposite ends of said of said leak preventing cuffs are bonded onto the inner surface of said main body.

4. A disposable diaper according to claim1, wherein each of said side flaps has an inner side edge surface portion bonded to an outer side edge surface of said main body in a region which lies beneath said liquid-absorbent core.

5. A disposable diaper comprising:

a main body for absorbing and containing body exudates, said main body including a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween, said liquid-absorbent core having front and rear ends, a pair of opposite side edges that are curved inwardly at least along a longitudinal middle portion thereof; and

a pair of elastically stretchable/contractile leak preventing cuffs formed by portions of at least one of said topsheet and backsheet which extend outward beyond transversely said pair of opposite side edges of said liquid-absorbent core, said leak preventing cuffs being collapsible inwardly of said main body onto said topsheet under an elastic bias which causes said leak preventing cuffs to rise up on said topsheet, each of said leak preventing cuffs including a lower portion that extends in a region defined between said side edge of said liquid-absorbent core and an outer fold line that extends longitudinally outside said curved edge of said liquid-absorbent core and an upper portion formed by folding an extension of said lower portion transversely of said main body along said outer fold line onto said topsheet, wherein elastically stretchable/contractile members extend longitudinally of said main body and are secured under tension to said leak preventing cuff at least in proximity of said outer fold line and in proximity of an inner side edge of said upper portion extending in parallel to said outer fold line; and

a pair of side flaps that extend outward from transversely opposite side edges of said main body, each of said side flaps being provided with an elastically stretchable/contractile member extending longitudinally of said side flap.

6. A disposable diaper according to claim6 wherein each of said side flaps has an inner side edge surface joined to an outer side edge of said main body in a region which lies beneath said core.

7. A disposable diaper according to claim6, wherein each of the leak preventing cuffs is bonded longitudinally opposite ends to said main body.

8. A disposable diaper according to claim8, wherein said longitudinal opposite ends of said leak preventing cuffs are bonded onto the inner surface of said main body.

9. A disposable diaper comprising:

a main body for absorbing and containing body exudates, said main body including a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid-absorbent core disposed therebetween, said liquid-absorbent core having front and rear ends, a pair of opposite side edges that are curved inwardly at least along a longitudinal middle portion thereof;

a pair of elastically stretchable/contractile leak preventing cuffs formed along transversely opposite side edges of said main body, said leak preventing cuffs extending longitudinally of said diaper and being collapsible inwardly of said main body onto an inner surface of said main body under an elastic bias which causes said leak preventing cuffs to rise up on the inner surface; and

a pair of side flaps extending outward from transversely opposite side edges of said main body and extending continuously across along a longitudinal length of the main body,

said liquid-absorbent core being defined by front and rear ends and a pair of opposite side edges, said side edges being curved inwardly at least along longitudinally middle portions thereof,

each of said leak preventing cuffs is at least partially formed by portions of at least one of said topsheet and said backsheet which extend outward beyond transversely opposite side edges of said core and includes a lower portion extending in a region defined between said side edge of said core and an outer fold line extending longitudinally outside said curved side edge of said core, each of said leak preventing cuffs further includes an upper portion formed by folding an extension of said lower portion directed transversely of said main body along said outer fold line onto said inner surface of said main body, wherein elastically stretchable/contractile members extending longitudinally of said main body are secured under tension to said leak preventing cuffs at least in the proximity of said outer fold line and in the proximity of an inner side edge of said upper portion extending in parallel to said outer fold line.

10. A disposable diaper according to claim10, wherein each of the leak preventing cuffs is bonded at longitudinally opposite ends to said main body.

11. A disposable diaper according to claim11, wherein said longitudinal opposite ends of said leak preventing cuffs are bonded onto the inner surface of said main body.

12. A disposable diaper according to claim10, wherein said diaper further comprises a pair of side flaps extending outward from transversely opposite side edges of said main body, each of said flaps having an inner side edge surface portion bonded to an outer side edge surface of said main body in a region which lies beneath said core.

13. A disposable diaper according to claim13, wherein each of said side flaps is provided with an elastically stretchable/contractile member extending longitudinally thereof.

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